It is well known that limiting the exposure of oxygen-sensitive products to oxygen maintains and enhances the quality and "shelf-life" of the product. For instance, by limiting the oxygen exposure of oxygen sensitive food products in a packaging system, the quality of the food product is maintained for a longer period of time, and food spoilage is reduced or delayed. In addition, such packaging also allows the product to be kept in inventory longer, thereby reducing costs incurred from waste and having to restock. In the food packaging industry, several means for limiting oxygen exposure have already been developed. At present, the more commonly used means include modified atmosphere packaging (MAP), and vacuum packaging using oxygen barrier film packaging. In such systems, reduced oxygen environments are employed in the packaging, and oxygen is physically prevented from entering the packaging environment. Also, packets containing oxygen scavenging agents are sometimes placed in a package for an oxygen sensitive article. Such packets are distributed by W. R. Grace and Co.--Conn. under the Ageless trademark.
Another, more recent, means for limiting oxygen exposure involves incorporating an oxygen scavenger into the packaging structure. Incorporation of a scavenger in the package can provide a uniform scavenging effect throughout the package. In addition, such incorporation can provide a means of intercepting and scavenging oxygen as it is passing through the walls of the package (herein referred to as an "active oxygen barrier"), thereby maintaining the lowest possible oxygen level throughout the package.
However, incorporating an oxygen scavenger into the packaging film itself typically requires a structural and/or compositional modification of a packaging film or laminate, in order to introduce the scavenging functionality to the film. This can in some cases compromise the film performance and properties compared with an unmodified film. It can also lead to an undesirably large inventory of different film products. In addition, the method of incorporation can limit the manufacturer's ability to tailor the nature and quantity of the scavenger to the particular film or laminate because of limitations in the method of manufacture, the degree of chemical and rheologic compatibility of the "host" film and the scavenger material during extrusion of the film, and other factors.
Thus, it is desirable to provide a discrete oxygen scavenger film strip which can be used in conjunction with a variety of packaging films and laminates, without the need to significantly modify the same films and laminates, structurally or chemically, for each desired end use.
It is particularly desirable to provide a sealed package where quantity of the active oxygen barrier is optimized based on the requirements of the particular package. That is, if a particular sealed package requires only a moderate amount of active oxygen barrier, one should be able to accommodate this without using excessive material and without undue experimentation and cost. Moreover, one should be able to accommodate a variety of different packaging requirements without maintaining a large inventory of different products.